Bone Preparation Research Articles

Observations of bony ongrowth and clinical fixation in two retrieved disc replacements.

Total disc replacements utilize textured coatings to maximize bony ongrowth. However, the contribution of direct bony attachment to overall fixation for total disc replacements has not been reported. The goal of the present study was to document the extent of bony attachment to the surfaces of two clinically functional total disc replacements that were securely fixed at the time of revision. Two metal-and-polymeric disc replacements, one cervical and one lumbar, were evaluated following surgical retrieval. The cervical device was retrieved at 8 months and the lumbar device at 28 months post-operative. Both devices were reported well-fixed at the time of removal, with large bone masses attached to one endplate of each device. Visual inspections, non-destructive gravimetric measurements, and surface metrology were performed to assess fixation. These inspections suggested that both devices had been fixed at the time of removal with little in vivo mechanical damage, as surgical extraction damage was noted on both devices and provided imaging showed a lack of device migration. Devices were then embedded and sectioned to evaluate the bone-implant interface. High resolution photographs and contact microradiographs were taken to assess bony attachment. In contrast to initial analysis, these images revealed radiolucent gaps between the endplates and bone masses. Little direct contact between the bone and endplate surface was identified and the original surgical cuts were still visible. Both devices were clinically fixed at the time of removal and neither had complications associated with loosening. However, osseointegration was minimal in one of the devices and altogether absent from the other. The findings of the present study suggest that other factors may influence overall clinical fixation such as the surgical preparation of the vertebral bone or the surface roughness of the treated endplates. Despite the limitations of the present study, this information is unique to the current total disc replacement literature and the ongrowth and fixation of devices should be considered as a topic for future investigation.

TORSIONAL LOAD MEASUREMENT DURING POSTERIOR APPROACH RANGE OF MOTION ASSESSMENT FOR TOTAL HIP ARTHROPLASTY

Range of Motion (ROM) assessments are routinely used during joint replacement to evaluate joint stability before, during and after surgery to ensure the effective restoration of patient biomechanics. This study aimed to quantify axial torque in the femur during ROM assessment in total hip arthroplasty to define performance criteria against which hip instruments can be verified. Longer term, this information may provide the ability to quantitatively assess joint stability, extending to quantitation of bone preparation and quality.Joint loads measured with strain-gaged instruments in five cadaveric femurs prepared using posterior approach were analysed. Variables such as surgeon-evaluator, trial offset and specimen leg and weight were used to define 13 individual setups and paired with surgeon appraisal of joint tension for each setup. Peak torque loads were then identified for specific motions within the ROM assessment.The largest torque measured in most setups was observed during maximum extension and external rotation of the joint, with a peak torque of 13Nm recorded in a specimen weighing 98kg. The largest torque range (19.4Nm) was also recorded in this specimen. Other motions within the trial reduction showed clear peaks in applied torque but with lower magnitude. Relationships between peak torque, torque range and specimen weight produced an R2 value greater than 0.65.The data indicated that key influencers of torsional loads during ROM were patient weight, joint tension and limb motion. This correlation with patient weight should be further investigated and highlights the need for population representation during cadaveric evaluation. Although this study considered a small sample size, consistent patterns were seen across several users and specimens. Follow-up studies should aim to increase the number of surgeon-evaluators and further vary specimen size and weight. Consideration should also be given to alternative surgical approaches such as the Direct Anterior Approach.

Biomechanical Characteristics and Analysis Approaches of Bone and Bone Substitute Materials

Bone has a special structure that is both stiff and elastic, and the composition of bone confers it with an exceptional mechanical property. However, bone substitute materials that are made of the same hydroxyapatite (HA) and collagen do not offer the same mechanical properties. It is important for bionic bone preparation to understand the structure of bone and the mineralization process and factors. In this paper, the research on the mineralization of collagen is reviewed in terms of the mechanical properties in recent years. Firstly, the structure and mechanical properties of bone are analyzed, and the differences of bone in different parts are described. Then, different scaffolds for bone repair are suggested considering bone repair sites. Mineralized collagen seems to be a better option for new composite scaffolds. Last, the paper introduces the most common method to prepare mineralized collagen and summarizes the factors influencing collagen mineralization and methods to analyze its mechanical properties. In conclusion, mineralized collagen is thought to be an ideal bone substitute material because it promotes faster development. Among the factors that promote collagen mineralization, more attention should be given to the mechanical loading factors of bone.

Intraoperative physician assessment of bone: correlation to bone mineral density.

Intuitively, intraoperative physician assessment (IPA) would be an excellent measure of bone status gained through haptic feedback during bone preparation. However, no studies have evaluated the orthopedic surgeon's ability to do so. This study's purpose, in patients undergoing total knee arthroplasty (TKA), was to relate IPA with (1) the lowest bone mineral density (BMD) T-score at routine clinical sites; and (2) with distal femur BMD. Seventy patients undergoing TKA by 3 surgeons received pre-operative DXA. Intraoperatively, bone quality was assessed on a 5-point scale (1 excellent to 5 poor) based on tactile feedback to preparation. Demographic data, DXA results, and IPA score between surgeons were compared by factorial ANOVA. Lowest T-score and distal femur BMD were associated with IPA using Spearman's correlation. The mean (SD) age and BMI were 65.8 (7.6) years and 31.4 (5.1) kg/m2, respectively. Patient demographic data, BMD, and IPA (mean [SD] = 2.74 [1.2]) did not differ between surgeons. IPA correlated with the lowest T-score (R = 0.511) and distal femur BMD (R = 0.603-0.661). Based on the lowest T-score, no osteoporotic patients had an IPA above average, and none with normal BMD was classified as having poor bone. IPA is highly correlated with local (distal femur) and overall BMD. This study supports the International Society for Clinical Densitometry position that surgeon concern regarding bone quality should lead to bone health assessment. As IPA is comparable between surgeons, it is logical this can be widely applied by experienced orthopedic surgeons. Future studies evaluating IPA at other anatomic sites are indicated.

THE INFLUENCE OF ANGULAR PARAMETERS OF THE LOWER JAW ON THE LOCALIZATION OF ITS FRACTURES IN AN ADULT

The frequency of mandibular fractures averages 45–90% of cases of all cases of damage to the bones of the facial skull. Cone-beam computed tomography is the most informative method for diagnosing pathological processes, the nature and degree of damage to the jaws, as well as when planning their surgical treatment, which allows assessing both the nature of the fracture and the value of the main parameters of the jaws necessary to create intraoperative templates. In order to study the sex and age characteristics of the angular parameters of the lower jaw and their interrelation with the nature of its fractures, a study was conducted on 150 bone preparations of the lower jaws and 300 computed tomograms of patients with fractures of the lower jaw. It was established that the angle of the condyle-coronoid line and the angle of the notch were significantly greater in men, and the angle of the lower jaw - in women. It has been proven that with age there is a significant change in the studied angular parameters, which is primarily associated with the loss of teeth. The values of the angle of the lower jaw in elderly and senile people are on average 11,2% higher than in adulthood, and the angle of the condyle-coronoid line significantly decreases with age by an average of 7°. It has been proved that when the value of the angle of the lower jaw is close to the right one, the fracture line is significantly more often localized in the area of the incisors in 31,7% of cases of observations, the canines and premolars - in 20,8% of cases of observations. Fractures in the area of the condylar process in women, unlike men, in the overall structure of fractures exceed the frequency of fractures in the area of its angle. Thus, the angular parameters of the lower jaw have pronounced gender and age differences, which have a direct impact on the nature and localization of fractures of this bone. As a result, the greater the angle of the lower jaw, the greater the likelihood of its single fractures, the smaller the angle of the condyle-coronoid line, the greater the likelihood of fractures in the area of the condylar process.

Mako Robotic-Arm Assisted Total Knee Arthroplasty

Total knee arthroplasty has been around for decades and serves as a very successful procedure to alleviate pain and restore function in a knee with advanced degenerative joint disease. Over the years, there have been many advancements in surgical technique and even more so in implant design. One of the more recent technological breakthroughs in total knee arthroplasty is the use of a robotic assisted arm for enhanced preoperative planning and intra-operative guidance with dynamic joint balancing and bone preparation. This video outlines the operative technique used by the primary author in performing a posterior stabilizing total knee arthroplasty in a varus deformity degenerative knee using Mako robotic assistance.

Patient-Specific Guides for Accurate and Precise Positioning of Osseointegrated Implants in Transfemoral Amputations: A Proof-of-Concept In Vitro Study

Background and Objectives: The treatment of transfemoral amputees using osseointegrated implants for prosthetic anchorage requires accurate implant positioning when using threaded bone-anchoring implants due to the curvature of the femur and the risk of cortical penetration in misaligned implants. This study investigated the accuracy and precision in implant positioning using additively manufactured case-specific positioning guides. Materials and Methods: The geometry and density distribution of twenty anatomic specimens of human femora were assessed in quantitative computed tomography (QCT) scanning. The imaging series were used to create digital 3D specimen models, preoperatively plan the optimal implant position and manufacture specimen-specific positioning guides. Following the surgical bone preparation and insertion of the fixture (threaded bone-anchoring element) (OPRA; Integrum AB, Mölndal, Sweden), a second QCT imaging series and 3D model design were conducted to assess the operatively achieved implant position. The 3D models were registered and the deviations of the intraoperatively achieved implant position from the preoperatively planned implant position were analyzed as follows. The achieved, compared to the planned implant position, was presented as resulting mean hip abduction or adduction (A/A) and extension or flexion (E/F) and mean implant axis offset in medial or lateral (M/L) and anterior or posterior (A/P) direction measured at the most distal implant axis point. Results: The achieved implant position deviated from the preoperative plan by 0.33 ± 0.33° (A/A) and 0.68 ± 0.66° (E/F) and 0.62 ± 0.55 mm (M/L) and 0.68 ± 0.56 mm (A/P), respectively. Conclusions: Using case-specific guides, it was feasible to achieve not only accurate but also precise positioning of the implants compared to the preoperative plan. Thus, their design and application in the clinical routine should be considered, especially in absence of viable alternatives.

AMS 14C dating of bioapatite: Advantage and disadvantage

Most methods of bone preparation for 14C dating are designed to extract collagen or individual compounds. The problem becomes acute for poorly preserved bones, since they have no collagen. The bioapatite is stable against microbiological decomposition and dissolution over millennium scales. However, it may be exposed to isotopic exchange with environmental carbonates.We are reviewing our research during the last decades comparing the dating different fractions of bones of different ages and differing preservation degrees. The results have shown that preservation of bioapatite depends on the conditions of the environment in which samples were buried. The wet environment affects bioapatite by enriching it with 14C due to isotopic exchange with environmental carbonates. 14C depletion of bone bioapatite deposited in caves and in limestone is possible. The results for the samples from arid, semi-arid and non-carbonate environments are in a good agreement with dates on other materials.

ROBOTIC-ARM ASSISTED UNICOMPARTMENTAL KNEE ARTHROPLASTY HAS A LEARNING CURVE OF 11 CASES AND INCREASED OPERATIVE TIME

Source of the study: University of Auckland, Auckland, New ZealandUnicompartmental knee arthroplasty (UKA) has benefits for patients with appropriate indications. However, UKA has a higher risk of revision, particularly for low-usage surgeons. The introduction of robotic-arm assisted systems may allow for improved outcomes but is also associated with a learning curve. We aimed to characterise the learning curve of a robotic-arm assisted system (MAKO) for UKA in terms of operative time, limb alignment, component sizing, and patient outcomes.Operative times, pre- and post-surgical limb alignments, and component sizing were prospectively recorded for consecutive cases of primary medial UKA between 2017 and 2021 (n=152, 5 surgeons). Patient outcomes were captured with the Oxford Knee Score (OKS), EuroQol-5D (EQ-5D), Forgotten Joint Score (FJS-12) and re-operation events up to two years post-UKA. A Cumulative Summation (CUSUM) method was used to estimate learning curves and to distinguish between learning and proficiency phases.Introduction of the system had a learning curve of 11 cases. There was increased operative time of 13 minutes between learning and proficiency phases (learning 98 mins vs. proficiency 85 mins; p<0.001), associated with navigation registration and bone preparation/cutting. A learning curve was also found with polyethylene insert sizing (p=0.03). No difference in patient outcomes between the two phases were detected for patient-reported outcome measures, implant survival (both phases 98%; NS) or re-operation (learning 100% vs. proficiency: 96%; NS). Implant survival and re-operation rates did not differ between low and high usage surgeons (cut-off of 12 UKAs per year).Introduction of the robotic-arm assisted system for UKA led to increased operative times for navigation registration and bone preparation, but no differences were detected in terms of component placement or patient outcomes regardless of usage. The short learning curve regardless of UKA usage indicated that robotic-arm assisted UKA may be particularly useful for low-usage surgeons.

Bone cutting efficiency and heat generation using a traditional fluted Burr and a novel fluteless resurfacing tool

BackgroundPowered instrumentation is often used for bone preparation and/or removal in many orthopaedic procedures but does risk thermogenesis. This study compares biomechanical properties of a fluted burr and a novel fluteless resurfacing tool. MethodsTwenty cadaveric metatarsals were tested with four predetermined cutting forces to evaluate heat generation and cutting rate for the fluted burr and fluteless resurfacing tool over 40 s or until a depth of 4 mm was reached. Cutting rate was calculated from displacement transducer data. Heat generation was measured by thermocouples placed in the bone adjacent to the burring site. Assuming a body temperature of 37 °C, a 10 °C increase in heat was used as the threshold of inducing osteonecrosis. FindingsAt 1.0 N and 1.7 N, the thermal osteonecrosis threshold was reached at comparable times between burrs, while the bone removed by the resurfacing tool was on average five times greater than fluted burr at 1.0 N and over twice as great at 1.7 N. Statistical analysis of these common cutting forces showed the resurfacing tool had significantly higher cutting rates (P < 0.01). As a result, the fluted burr produced higher temperatures for the same amount of bone removal (P < 0.01). InterpretationIn a cadaveric study, the fluteless resurfacing tool demonstrated higher bone cutting rates and lower heat generation for the same amount of bone removed than a traditional fluted burr.

Procurement and processing of human bones in medical schools for teaching purpose: A narrative review

Bones are an indispensable learning resource to learn osteology. This study reviews the various bone preparation techniques and the ease of procurement and processing of human bones for teaching medical students and osteology research. Steps of bone preparation essentially involve soft tissue removal, bone bleaching, bone articulation and labelling. Embalmed cadavers may be ideal for bone preparation because it eliminates the risk of infection. Detergent maceration may be the ideal method of bone maceration because it is a cheaper technique and gives good results. Both acetone and hydrogen peroxide may be the ideal degreasing and bleaching agents, owing to their superior outcomes. Embalmed cadavers may be ideal for bone preparation because it eliminates the risk of infection. Among all, detergent maceration can be considered as the ideal method because of its cost-effectiveness and good results. Both acetone and hydrogen peroxide can be considered as the ideal degreasing and bleaching agents, owing to their superior outcomes.

Preparation and properties of artificial bone with lead-free piezoelectric materials

In order to fabricate the artificial bone with high bioactive property, lead-free barium titanate (BaTiO3, BT) piezoelectric material added hydroxyapatite (HA) composites were prepared in this study. Compared with the pure HA materials, the introduction of BT can increase the electrical properties of the samples while ensuring good biological properties. The electrical properties, such as piezoelectric constant d33, hysteresis loop and dielectric spectrum were measured, respectively. The bending strength, Vickers hardness, cytotoxicity and osteogenic property of the BT/HA composites were also discussed. It is revealed that the non-toxic sample with 95 wt% BT and 5 wt% HA (95BT+5HA) has the best osteoinductivity, the piezoelectric constant d33 of which is 79.2 pC N-1. The bending strength and Vickers hardness of the 95BT+5HA sample are 138.3 MPa and 472.4, respectively, realizing the desired mechanical properties of human bones. Comprehensive analyses of various properties show that the 95BT+5HA composite can meet the requirements of artificial bone, and is expected to be a promising generation of substitute bone materials.

Determination of the position of the openings of the facial part of the skull in relation to craniological points and bony landmarks depending on the facial index of a person of mature age

Annotation. Knowing the exact position of the openings in the facial part of the skull, through which vessels and nerves pass, is extremely important for performing operative, reconstructive and other interventions in this area. Since there is considerable variability in the position of the supraorbital (SOH), infraorbital (IOH) and submental (SMOH) holes, the purpose of our work is to determine the exact spatial position of the above-mentioned holes relative to cranial points and bony landmarks depending on the facial index of a mature person. Studies were conducted on 52 bone preparations of skulls using commonly accepted instruments and 60 CT images of mature Caucasians without pathology of the bones of the facial part of the skull. Studies on CT images were carried out using a virtual Anatomage table using the Launching Table 6.0 Application program. Statistical methods were used to analyze the obtained measurement results in our research, which was carried out with the help of the Microsoft Excel 2010 © licensed program package and with the help of the “STATISTYCA” program. To determine the interdependence of features in the general population, a correlation analysis was performed. In the course of the study, we determined the average values of the distances from the SOH, IOH and SMOH to the following craniological points: nasion (n.), nasospinale (ns) and frontomalare orbitale (fmo) depending on the facial index. Analyzing the obtained data, significant differences in the position of the above-mentioned openings to the corresponding craniological points were clearly observed depending on the type of structure of the facial part of the skull. There was an increase in the distances from the SOH and IOH to the nasion point and the frontmolar orbital point in euryprosopics, and smaller results were obtained in leptoprosopics. The average values of the distance indicators from the SOH, IOH and SMOH to the nasolabial point were significantly larger in leptoprosopics, in contrast to euryprosopics. When determining the size of the supraorbital margin and the distance from the SOH to the supraorbital margin, euryprosopics prevailed. The obtained results of measuring the distance from the IOH to the edge of the upper jaw and from the SMOH to the upper and lower edges of the lower jaw indicate an increase in these distances in long-faced (leptoprosopic) in contrast to wide-faced (euryprosopic). The results of the study indicate the dependence of the position of the openings of the facial part of the skull on the facial index, which will make it easier in clinical practice to determine the position of the nerves and vessels coming out of these openings.

Teratogenic Toxicity of Ethanol Extract of Mahkota Dewa Fruit Flesh (Phaleria macrocarpa (Scheff.) Boerl)

Mahkota Dewa is known as one of the medicinal plants in Indonesia. It contains bioactive compounds and potentially has pharmacological activity. This study aimed to determine the possible toxic effects of Mahkota DewaThe ethanol extract of Mahkota Dewa fruit flesh was given to rats. Group I (control 0.5% Na-CMC), groups II, III and IV as a treatment group (Mahkota Dewa at doses of 100, 500 and 1000 mg/kg bw, respectively). Group V as a control satellite (Na-CMC 0, 5%) and group VI as a satellite of the ethanol extract at a dose of 1000 mg/kg bw., Each groups were treated on day 6 to 15 of gestational. On the 19th day getation, the rats were dissected and observed the skeletal malformations. The data were analyzed using one-way ANOVA followed by a post-hoc tukey. The results toxicity showed that no fetuses had external malformations. On fetal skeletal appearance, all skeletal bone preparations were normal. Based on the study, the ethanolic extract of Mahkota Dewa Fruit Flesh did not cause a teratogenic effect on the fetus during the organogenesis period at doses of 100 mg/kg bw, 500 mg/kg bw, and 1000 mg/kg bw

Preparation of bone of Rhesus monkey (Macaca mulatta) without use of Chemical

Preparation of bone of Rhesus monkey (Macaca mulatta) without use of Chemical

Morphological and morphometric studies on the axial skeleton of the sitatunga (Tragelaphus spekii gratus)

BackgroundAnatomical features of the skeleton of wild animals contribute largely to their adaptation. A dearth of information on the skeletal anatomy of the sitatunga (Tragelaphus spekii gratus) necessitated this study. Two adult sitatunga carcasses weighing 54 kg and 57 kg were obtained after post-mortem examination. Bone preparation was achieved through cold water maceration protocol.ResultThe tympanic bulla was elongated and massive, resulting in the rudimentary appearance of the styloid and muscular processes of the temporal bone. The lacrimal bone had a somewhat triangular presentation with the lacrimal foramen on the caudal border of the facial surface while its dorsal border formed the lateral margin of the frontal sinus. There was no observable lacrimal fossa on this facial surface of the lacrimal bone. The facial tubercle was absent. The vertebral column formula was C7 T13 L6 S4 C10-14, and the atlas dorsal median tubercle was smooth, devoid of ridges. The spinous process of the axis extended the entire arch length to hang little above the odontoid process. The thoracic spinous processes were oriented dorso-caudally from T1 to T11; spinous process of T12 was vertical, while that of T13 was oriented dorso-cranially. The length of the transverse process of L1 and L6 were the same, and smaller than the length of those of L2-L5. There was incomplete fusion of sacral spinous processes. Three dorsal and ventral sacral foramina were identified laterally on each side of the vertebrae. The ribs were 26 in number (13 pairs). The sternum was comprised of 5 sternabrae separated by intersternal cartilage. The average number of bones of the axial skeleton was 75. Morphometric in formation included the length of skull, mandible and ribs; body length of vertebrae and spinous process length and height of the vertebrae.ConclusionThis study recorded anatomical features and biometric information on axial skeletal bones of the Sitatunga (Tragelaphus spekii gratus) thereby providing baseline data for future biomedical, archaeological and comparative skeletal anatomical studies.

Effects of four different methods of skeletal processing on the guinea fowl (Numida meleagridis).

The process of skeletal processing which involves soft tissues removal, bone cleaning, articulation and labelling is a fundamental step in achieving gross anatomical and archeological studies in museum display of skeletal specimens. It also helps to further highlight the functional anatomy of bones. Several methods of bone preparation have been practiced so as to achieve desired quality bone specimens in the shortest possible time with limited resources. To this end, this study was carried out on 16 (8 males and 8 females) helmeted guinea fowl (Numida meleagridis) a representative of the avian species using four different bone preparation methods (Burial, cold maceration, chemical and insect larvae) at 31ºc to determine the most suitable in this species. Dissection to remove feathers, skin and internal organs was performed prior to each method. Burial in soil took 14 days for complete bone recovery, turned the bones uniformly light brown while producing an indelible putrefying smell with no evidence of cracks on the bones. Cold maceration also took 14 days for complete bone recovery, however, the bones turned whitish, producing a strong putrid smell with no cracks on the bones observed. Chemical method using 3 concentrations of sodium hydroxide (NaOH) (2%, 3% and 5%) took approximately 10 hours, 8 hours and 4 hours respectively for complete cream coloured bone recovery with no odour but cracks were conspicuous on the bones with increasing concentration of sodium hydroxide. Use of insect larvae took approximately 4 months to produce non-uniform brown-coloured bones articulated via the ligaments having an unpleasant odour with no cracks. Considering the pros and cons of the effects associated with each method, this study concludes that the use of insect larvae was most suitable for a non-urgent bone recovery while the use of NaOH at 3% concentration was suitable for urgent bone recovery of the helmeted guinea fowl.

Numeric and morphological studies of the African lion (Panthera leo leo) pectoral limb

BackgroundThe Importance of the appendicular skeleton in the conformation, shape and physiology of wild animals especially carnivores for adaptation and survival cannot be overemphasized, as limited and obsolete information on the bones of the forelimb necessitated this study. Matured adult African lions (Male and female) that weighed 173 kg and 112 kg were obtained at different times after post mortem examinations of their carcasses. Bone preparation was achieved via cold water maceration after proper skin and muscle removal to a barest minimum.ResultsThe acromion process of the scapula consisted of a ventral hamate and caudal suprahamate processes. The Clavicle was absent in this species. The musculospiral groove of the humerus was more or less absent while its supracondyloid foramen and crest were positioned above the medial condyle and lateral condyle respectively. The radio-ulna presented a twisted appearance with the radius slightly curved thereby creating an extensive interosseous space that spanned its entire length. The seven (7) carpal bones were uniquely arranged in two rows while the 5 metacarpals anchored 5 digits with 3 phalanges except the first with 2 phalanges each. Two sesamoid bones were located on the ventral surface of each Metacarpophalangeal joint. None was seen on its dorsal surface. The 3rd phalanx had a unique appearance with a crescent plate projecting from the ventral cavity. The average total number of bones constituting the pectoral limb was 80.ConclusionNumerical information and detailed anatomical features of the pectoral limb bones of the African lion (Panthera leo leo) have added some valuable literature to science. This further serves as a baseline data for future scientific exposition on this species.

Establishment of the gender of rabbits by craniometric and morphological features of the skull

Introduction. Sexual dimorphism in rabbits is poorly expressed, which creates a number of difficulties in determining the sex of the animal. The need to determine sex arises during forensic veterinary examination, archaeological and special morphological studies, as well as in the study of age and breed variability of animals using craniological material. This issue is especially relevant for veterinary and sanitary examination, since the sex of the animal can affect the quality of wool or the taste of meat, which affects the quality of the products obtained.Objects and methods. The objects of the study were skulls (n = 4) of Californian breed ofrabbits and skulls (n = 4) of Soviet chinchilla breed. The stages of the study were: the creation of 8 bone preparations by boiling them in water with the addition of bicarbonate of soda, bleaching in a 3% hydrogen peroxide solution, comparison and morphometry.Results. Based on the study, it is possible to identify craniological features characteristic of male and female rabbits: the angle of the lower jaw in males is thicker and more massive, has a more pronounced masticatory fossa; supraorbital processes of male rabbits are more branched and wide; the zygomatic process of the zygomatic bone has a thin elongated shape in females, and a wide oval in males; on the horizontal plate of the palatine bone of femalerabbits there is large number of holes; in males, the lattice opening resembles a cello in shape, and the pituitary gland resembles an oval; the occipito-sphenoid fusion in male rabbits is convex, and the occipital crest has a thickening. Thanks to the use of several breeds of rabbits in the experiment, it can be proved that these patterns relate to sex, and not to breed. The results of the study can be used to determine the sex of an animal by the skull or its fragments, which is important for forensic veterinary examination when using a craniological method for determining the sex of various animal species.

Robotic-arm assisted total knee arthroplasty has a learning curve of 16 cases and increased operative time of 12 min.

Robotic-arm assisted systems are increasingly used for knee arthroplasty, however introduction of new systems can involve a learning curve. We aimed to define the learning curve in terms of operative time and component placement/sizing of a robotic system for total knee arthroplasty (TKA) in a team of experienced surgeons, and to investigate mid-term patient outcomes. A total of 101 consecutive patients underwent primary robotic-arm assisted TKA by three surgeons (mean 2year follow-up). Operative times, component placement, implant sizing and reoperations were recorded. Cumulative Summation (CUSUM) was used to analyse learning curves. Patient outcomes were compared between learning and proficiency phases. The learning curve was 16 cases, with a 12-min increase in operative time (P< 0.01). Once proficiency was achieved, the greatest time reductions were seen for navigation registration (P= 0.003) and bone preparation (P< 0.0001). A learning curve was found with polyethylene (PE) insert sizing (P= 0.01). No differences were found between learning and proficiency groups in terms of implant survival (100% and 97%, respectively, NS) or patient-reported outcome measures at 2 years (NS). Introduction of a robotic-arm assisted system for TKA led to increased operative times for navigation registration and bone preparation, and a learning curve with PE insert sizing. No difference in patient outcomes between learning and proficiency groups at 2 years was found. These findings can inform surgeons' expectations when starting to use robotic-assisted systems.